(3S,4R)-3-ethyl-4-(3H-imidazo[1,2-a]pyrrolo[2,3-e]pyrazin-8-yl)-N-(2,2,2-trifluoroethyl)pyrrolidine-1-carboxamide (“Compound 1”) was first disclosed in International Application WO2011/068881A1, which is herein incorporated by reference in its entirety. The compound has activity as a Janus kinase (“JAK”) inhibitor, particularly as a JAK-1 inhibitor. Clinical trials are ongoing to evaluate the use of the compound to treat rheumatoid arthritis.
The isolation and commercial-scale preparation of a solid state form of Compound 1 and corresponding pharmaceutical formulations having acceptable solid state properties (including chemical stability, thermal stability, solubility, hygroscopicity, and/or particle size), compound manufacturability (including yield, impurity rejection during crystallization, filtration properties, drying properties, and milling properties), and formulation feasibility (including stability with respect to pressure or compression forces during tableting) present a number of challenges that are discussed in greater detail below. Accordingly, there is a current need for one or more solid state forms of Compound 1 that have an acceptable balance of these properties and can be used in the preparation of pharmaceutically acceptable solid dosage forms.
Additionally, currently known processes for the preparation of Compound 1 involve the use of particularly hazardous reagents, such as trimethylsilyldiazomethane or diazomethane, and do not produce a crystalline product. There is thus also a need for a process for preparing Compound 1, and pharmaceutically acceptable salts thereof, that avoids the use of particularly hazardous reagents, and can produce a crystalline product and crystalline intermediates.
Additionally, sustained peak plasma concentrations can theoretically be achieved by means of sustained release matrix systems. However, when such systems are made of hydrophilic polymers, such as HPMC, they seldom provide pH independent drug release of pH-dependent soluble drugs, and they are normally incapable of attaining zero-order release except for practically insoluble drugs. Unexpectedly, is has been discovered that when tartaric acid is used as a pH-modifier in such a system, it allows Compound 1 to be released at a steady rate regardless of the pH of the environment.
In an unexpected finding, it was discovered that as a tablet containing the hydrophilic polymer matrix system erodes, Compound 1 reacts with the HPMC, creating a thicker gel layer which slows the release of Compound 1 from the tablet. The resulting gel layer provided an environment suitable for Compound 1 to dissolve.